Research into Methyl Bromide Alternatives

UC researchers are helping growers find alternatives to methyl bromide. Sabrina Hill reports.Click to Open or Download Audio Report
Since the 1960’s, California growers have used the soil fumigant methyl bromide to sterilize fields before planting. It is very effective in keeping invasive pests out of crops and controlling soilborne diseases. But starting in the 1990’s an international ban has forced a phase out of the chemical, until it was banned completely in 2005. It’s now only allowed in what the EPA calls “critical use” situations, which are carefully regulated by the government agency, and will only be allowed for a few more years.

University of California researchers are working to help growers find substitutes for methyl bromide. They’re part of a team of UC and United States Department of Agriculture researchers, who are working with a five million dollar grant on a project called the Pacific Area-Wide Pest Management Program for Integrated Methyl Bromide Alternatives. It includes production crops like grapes, strawberries and tree nuts as well as nursery crops.

In strawberries, the main use of methyl bromide was to control soilborne diseases. The research team has found some non-toxic alternatives that work on a small scale, including nonsoil substrates, anaerobic soil disinfestation and steam disinfestations. When using these methods on the small scale, the yields were as high as those in conventionally fumigated soil. But again, that was on the small scale and only in the test growing area. the next step in the strawberry research is to see if these alternative methods can be used in large commercial production fields, and if they work in California’s different berry-growing regions.

In almonds and stone fruit, methyl bromide is used to control nematodes as well as disease. Researchers are testing alternative fumigants, spot and strip fumigation and nonfumigant methods like crop rotations and the use of nematode-resistant rootstock.

For nursery stock, which includes stock for the state’s fruit, nut and vineyard industries as well as ornamental plants, researchers are working with alternative fumigants. They’re troubleshooting why some of the fumigants don’t work as well in fine soil and are finding that application changes may help.

Their results so far are published in the summer issue of California Agriculture, UC’s peer-reviewed journal of research in agricultural, human and natural resources.